A three-man crew has arrived at the International Space Station, after a two-day trip in a Russian Soyuz spacecraft. Two of the men will replace the crew now on the station as part of the normal six-month rotation.

There were smiles and hugs as the station hatch opened.

Two Russian cosmonauts and one American astronaut joined the two men who have been on board the space station for the past six months.

The hatch opening came three hours after a difficult docking, in which the commander of the Soyuz had to switch to manual mode, when he saw the craft was approaching the space station too rapidly.

Russian officials at mission control outside Moscow breathed a sigh of relief that, in the end, all went well.

American Leroy Chiao and Russian Salizhan Sharipov will replace Michael Fincke and Gennady Padalka for a new six-month mission that will feature experiments in plant growth and testing vaccines to combat AIDS.

Soyuz spacecraft have served as the only link with the space station, since NASA grounded all American space shuttles after the Columbia shuttle disaster last year that killed all seven astronauts on board.